What is the destiny of primary xylem in a dicot root showing extensive secondary growth?

1. It is retained in the centre of the axis

2 It gets crushed

3. May or may not get crushed

4. It gets surrounded by primary phloem

Anatomically fairly old root is distinguished from dicotyledonous stem by

1. Position of Protoxylem

2. Absence of secondary xylem

3. Absence of secondary phloem

4. Presence of cortex

Secondary growth is because of

1. vascular cambium

2. cork cambium

3. lateral meristem

4. All of the above

Secondary growth occurs in

(1)dicot root and stem of angiosperms

(2)dicot root and stem of gymnosperms

(3)monocot roots

(4)Both 1 and 2

For a critical study of secondary growth in plants, which one of the following pairs is suitable:

1. Sugarcane and sunflower

2. Teak and pine

3. Deodar and Fern

4. Wheat and maidenhair fern

In dicot roots, secondary phloem is formed towards the _________ and secondary xylem is formed towards the __________ by the activity of vascular cambium.
1.periphery, centre
2.centre, periphery
3.innerside, outerside
4.Both 2 and 3

Dicot roots do not have cambium in vascular bundles, but secondary growth cambium is served from

1. Pericycle cells only

2. Pericycle and conjunctive tissue

3. Conjunctive tissue only

4. Pericycle and cortex

During secondary growth in dicot root 

1. Vascular cambium arises completely from conjunctive parenchyma

2. Growth rings are distinct with spring wood alternating with autumn wood 

3. Phellogen arises from the epidermis

4. Vascular cambium is complete and continuous wavy ring